بانک‌های اطلاعاتی – پایگاه داده -dataset

بانک‌های اطلاعاتی – پایگاه داده -dataset

اسلاید 1: به نام آنكه جان را فكرت آموختاحمد مرادیبانک‌هاي اطلاعاتي

اسلاید 2: نسلهاي مختلف در ارتباط با ذخيره سازي و بازيابي اطلاعات وجود داشته است. در يك مقايسة اوليه روشهاي مورد استفاده در دو دستة ذيل بررسي مي‌شود: روش هاي سنتي روش مدرن ذخيره سازي و بازيابي اطلاعات

اسلاید 3: The organization has multiple applications with related data filesEach application has a specific data file related to it, containing all the data records needed by the applicationEach application comes with an associated application-specific data fileTraditional File Environment

اسلاید 4: Traditional File Environment

اسلاید 5: Data redundancy – same piece of data found in several places.Data inconsistency – various copies of data no longer agree.Data isolation – data in several application data files is hard to access and integrate.Security – may be difficult to limit access to various data items in applications.Data integrity – data must be accurate and correct.Application/data dependence – applications are developed based on the way data is stored.)low isolation)Problems: Traditional File Environment

اسلاید 6: Database Management System (DBMS)Database : The Modern ApproachThe database management system(DBMS) provides access to the data

اسلاید 7: مجموعة داده هاي ذخيره شده ( در ارتباط با موضوع)به صورت مجتمع و مبتني بر ساختار تعريف شده با افزونگي كم ، تحت كنترل متمركز و قابل استفاده براي يك يا چند كاربر بصورت مشترك را گويند. سيستم مديريت بانك داده‌ها (اطلاعات)DBMS چيست؟سيستمي كه امكان نگهداري داده‌ها ، بازيابي، تغيير ، اضافه و حذف آنها را توسط كاربر ميسر مي‌كند.بانك داده‌ها (اطلاعاتي) يا پايگاه داده‌ها چيست؟

اسلاید 8: Two choices: Centralized or Distributed(متمركز يا توزيعي)Choice will affect: user accessibility, query response time, data entry, security, and costOption 1: Centralized databaseAll the related files are in one physical locationProvides database administrators with the ability to work on a database as a whole at one locationData consistency is improved and security is easierFiles are only accessible via the centralized host computerRecovery from disasters is easierVulnerable to a single point of failureSpeed problem due to transmission delaysLocating Data in Databases (Two Choices)

اسلاید 9: Option 2: Distributed databaseComplete copies of a database, or portions of a database, are in more than one location, close to the userType 1: Replicated databaseCopies of database in many locationsReduced single-point-of-failure problems Increased user access responsivenessType 2: Partitioned databases A portion of the database in each locationEach location responsible for its own dataLocating Data in Databases (continued)